This invention relates to a numerical control system employable for controlling machine tools and the like. More specifically, this invention relates to a numerical control system having a function of graphically displaying the sequential progress or operational positions of any of the control elements controlled by the numerical control system, in an arbitrarily selected manner in terms of e.g. display format, time scale (which is defined as a length of time to be represented by a unit geometrical length of a display), display starting time, or the like.
The essential components of a numerical control system are a central processing unit, a memory means and an input-output means. Although a display means is not necessarily included in the essential components of a numerical control system, the display means is extremely convenient for finding various errors caused by user operations and/or various errors relating to the items of user operations e.g. program errors, control errors, etc. and/or for finding malfunctions in the numerical control system proper. Further, the display means is useful for monitoring the sequential progress of machining conducted by a machine tool controlled by a numerical control system. Since a display means is thus a significant benefit for a numerical control system, a numerical control system is usually equipped with a display means. Particularly, the items relating to user operations are preferably displayed.
In addition, a programmable controller is preferably employed as the sequential control unit of a power panel which functions as the interface connecting a numerical control system and a machine tool controlled therewith, because it is convenient for compiling and testing a program (e.g. a sequential control program or the like). A programmable controller is defined as an additional computer including a processing unit, a memory means, and an input-output means in some cases, for supplementing the function of a main computer which the programmable controller is attached to. The programmable controller receives inputs of various information including the information which a user inputs in an input-output means of the numerical control system, the information picked up by sensors attached to a machine tool controlled by the numerical control system, and the information input by the numerical control system. The information input to this programmable controller is processed under the control of the program of the programmable controller, before the results of the processing are input to the numerical control system and/or the machine tool. In other words, a programmable controller is a supplemental computer having an individual specification and being designed and installed independently of a numerical control system which is inclined to have a fixed or non-flexible specification due to the potential advantage of mass production. The programmable controller applies preparatory processes to the information predominantly relating to user's operations and inputs the results of the preparatory processes to a numerical control system and/or a machine tool. Accordingly, a means for displaying the information inputted and/or outputted by a programmable controller, provides considerable advantages. This invention relates to an improvement applicable to a display means which is attached to a numerical control system including a programmable controller.
In the prior art, a numerical control system having a programmable controller and a display means, uses numerals as media for displaying control elements. However, since such a display, presented in the form of numerals, is arranged in the format of a program list, it is generally difficult to display the sequential progress or operational positions of plural control elements which relate to one another in one picture. Thus, it is clear that a display means having the functions itemized below would be extremely useful from the industrial viewpoint:
i. a function of graphically displaying, in one picture displayed with a time scale (which is defined as a length of time to be represented by a unit geometrical length of a display) most convenient to observe, a group of information elements each of which resides remote from the other in a program but which relate to each other from a functional viewpoint, the information elements being selected from plural addresses remote from one another;
ii. a function of displaying the above information elements not only as a one-shot type still picture but also as a set of repetitive pictures, which is defined as a set of plural pictures cyclically appearing on a screen to represent the operational positions of the same set of control elements at a different time range, such a cyclical display being triggered by cyclical generation of a trigger signal; and
iii. a function of displaying a sequential progress or operational positions of the above set of information elements which occurs some time later than the time at which a display command is issued, in a specific environment in which such a delayed display is convenient for some reason relating to the function of a machine tool with which the numerical control system is employed.